Proactive Uplink Interference Management for Nonuniform Heterogeneous Cellular Networks

In homogeneous cellular networks, fractional power control (FPC) is employed to partially compensate the path-loss and, hence, improve uplink (U-L) signal-to-interference ratio (SIR). However, this scheme is less effective in heterogeneous cellular networks (HetNets) because: (i) except the typical user, all other users with variable U-L transmit power (UTP) act as interferers, (ii) FPC leads to high UTP by edge users and, hence, more interference, and (iii) small base stations (SBSs)' densification further increases network interferences. Leveraging FPC in HetNets, we propose nonuniform SBS deployment (NU-SBSD) to reduce interference and, thus, increase network performance. According to our NU-SBSD model, SBS deployment (SBSD) near macro base station (MBS) is avoided, whereas MBS coverage edge area is enriched with ultra-dense SBSD. NU-SBSD model leads to: (i) better SIR reception of MBS coverage edge users, (ii) fewer SBS D requirement, and (iii) better SBS coverage in the MBS coverage edge area. Moreover, to make a model more proactive, we also consider reverse frequency allocation (RFA) to further abate both U-L and downlink (D-L) interferences. The coverage probability expressions are derived for both uniform SBS deployment (U-SBSD) and NU-SBSD while using RFA and FPC. Through simulation and numerical results, we characterize coverage probability for different values of SIR threshold, path loss compensation factor, SBS density, users density, and the distance between the typical user and the associated base station. The proposed NU-SBSD model along with RFA leads to reduced network interference as compared with U-SBSD and, thus, leverages FPC in HetNets.